mirror of
https://github.com/zhigang1992/react-native.git
synced 2026-04-18 12:12:15 +08:00
b6e42517e5
Summary: This diff implements a new model of managing `enabled` flag in EventEmitter. Now we simply rely on `eventTarget_` is not being `nullptr` (and we reset the pointer to "disable" the event emitter). Reviewed By: mdvacca Differential Revision: D9764857 fbshipit-source-id: 1dd3ce0c8589048babbf2dbac9f8359358b31a34
95 lines
2.1 KiB
C++
95 lines
2.1 KiB
C++
/**
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#include "EventEmitter.h"
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#include <folly/dynamic.h>
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#include "RawEvent.h"
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namespace facebook {
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namespace react {
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// TODO(T29874519): Get rid of "top" prefix once and for all.
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/*
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* Capitalizes the first letter of the event type and adds "top" prefix
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* (e.g. "layout" becames "topLayout").
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*/
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static std::string normalizeEventType(const std::string &type) {
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auto prefixedType = type;
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prefixedType[0] = toupper(prefixedType[0]);
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prefixedType.insert(0, "top");
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return prefixedType;
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}
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std::recursive_mutex &EventEmitter::DispatchMutex() {
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static std::recursive_mutex mutex;
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return mutex;
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}
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EventEmitter::EventEmitter(
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SharedEventTarget eventTarget,
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Tag tag,
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WeakEventDispatcher eventDispatcher
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):
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eventTarget_(std::move(eventTarget)),
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tag_(tag),
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eventDispatcher_(std::move(eventDispatcher)) {}
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void EventEmitter::dispatchEvent(
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const std::string &type,
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const folly::dynamic &payload,
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const EventPriority &priority
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) const {
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const auto &eventDispatcher = eventDispatcher_.lock();
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if (!eventDispatcher) {
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return;
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}
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// Mixing `target` into `payload`.
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assert(payload.isObject());
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folly::dynamic extendedPayload = folly::dynamic::object("target", tag_);
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extendedPayload.merge_patch(payload);
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auto weakEventEmitter = std::weak_ptr<const EventEmitter> {shared_from_this()};
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eventDispatcher->dispatchEvent(
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RawEvent(
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normalizeEventType(type),
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extendedPayload,
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eventTarget_,
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[weakEventEmitter]() {
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auto eventEmitter = weakEventEmitter.lock();
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if (!eventEmitter) {
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return false;
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}
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return eventEmitter->getEnabled();
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}
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),
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priority
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);
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}
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void EventEmitter::setEnabled(bool enabled) const {
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bool alreadyEnabled = eventTarget_ != nullptr;
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if (enabled == alreadyEnabled) {
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return;
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}
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if (!enabled) {
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eventTarget_.reset();
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}
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}
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bool EventEmitter::getEnabled() const {
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return eventTarget_ != nullptr;
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}
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} // namespace react
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} // namespace facebook
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